/**
 * This file is part of Logisim-evolution.
 *
 * Logisim-evolution is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by the
 * Free Software Foundation, either version 3 of the License, or (at your
 * option) any later version.
 *
 * Logisim-evolution is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with Logisim-evolution.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Original code by Carl Burch (http://www.cburch.com), 2011.
 * Subsequent modifications by:
 *   + Haute École Spécialisée Bernoise
 *     http://www.bfh.ch
 *   + Haute École du paysage, d'ingénierie et d'architecture de Genève
 *     http://hepia.hesge.ch/
 *   + Haute École d'Ingénierie et de Gestion du Canton de Vaud
 *     http://www.heig-vd.ch/
 *   + REDS Institute - HEIG-VD, Yverdon-les-Bains, Switzerland
 *     http://reds.heig-vd.ch
 * This version of the project is currently maintained by:
 *   + Kevin Walsh (kwalsh@holycross.edu, http://mathcs.holycross.edu/~kwalsh)
 */

package com.cburch.logisim.util;

/**
 * Allows immutable objects to be cached in memory in order to reduce the
 * creation of duplicate objects.
 */
public class Cache<E> {
  private int mask;
  private Object[] data;

  public Cache() {
    this(8);
  }

  public Cache(int logSize) {
    if (logSize > 12)
      logSize = 12;

    data = new Object[1 << logSize];
    mask = data.length - 1;
  }

  public E get(int hashCode) {
    return (E) data[hashCode & mask];
  }

  public E get(E value) {
    if (value == null)
      return null;
    int code = value.hashCode() & mask;
    E ret = (E) data[code];
    if (ret != null && ret.equals(value)) {
      return ret;
    } else {
      data[code] = value;
      return value;
    }
  }

  public void put(int hashCode, E value) {
    if (value != null) {
      data[hashCode & mask] = value;
    }
  }
}
